Many people here make the suggestion to tell TSA employees to "pound sand". Perhaps in reaction to these suggestions the TSA has reclassified sand as a liquid, and thus one would have to leave the secure area to pound it.

The sign I've seen posted is something like: "If it POURS�SPREADS�SQUEEZES..or.. SPRAYS it's a liquid."

Sand is clearly a liquid. So is Jr's teddy-bear. I won't even suggest some of the things that can be "spread".

Which, in TSA Newspeak, clearly and completely explains why a solid block of ice is considered a prohibited liquid.

But I have now twice carried cremated human remains on board without a problem. And, if you've ever seen those, I'd call it quite similar to sand.

At some point, at a certain temperature, so will you, right? Therefore, you should not be permitted through the security checkpoint, either.

Correct! if you want to placed sand into checked bags before you flying out next time. You should not able take it onboard by entire aircraft. I believe Hawaii is allowed to do inspected the bags by special x-ray machines. It's more reasonable that you considered leave the sand in Hawaii instead of flying on the planes. It's could be some extremely dangerous for that.

You're already 80% water, and it's probably in a container over 3oz. too.

if its frozen solid, shouldn't you be able to tell its not an explosive?

if i had a block of ice frozen in my bag the shape of a pair of socks, would you guys even see it? or is it only when its shaped like a bottle?

50�F is well above freezing(H2O), so ice wouldn't be necessary.

If I remember OrgChem 211 correctly, liquid nitroglycerine actually is dangerous in amounts under 3oz.

Does medical nitroglycerine set off the sniffer/swabs? How should someone who needs it deal with it in carry-on? Checked luggage?

�except for the fact that it freezes at -346.0�F (-210.0�C) so there are are just a few eensy-weensy handling issues that can help distinguish it from water ice. Grimacing, odd movements, and screams of pain generated by 2�-3� freeze burns, or the presence of large asbestos mitts and tongs, might tip off SPOTters, screeners, or anybody else on the concourse.

For fun with liquid nitrogen (one phase change warmer, lots drippier, and still requiring protective equipment), try this: http://www.polsci.wvu.edu/Henry/Icecream/Icecream.html

The problem with using nitroglycerine to blow up what you intend to blow up is 1) instability and 2) difficult storage. That's why dynamite replaced it for industrial use�which is much bulkier and requires a separate ignition source.

Just pills AFAIK. As you've seen it's a common prescription; does it cause false-positives regularly during the screening process?

(I often travel with cheese so I've learned to alert the screeners. At one checkpoint they even had a song about it, with such great barbershop-quartet harmony I forgot to complain about the waste of my tax dollars.)

cool, just wondering if there was reasoning for all this...

thanks!

Thass okay, I'm a sci/soc sci major who passed the first-level State Dept Exam due solely to what I learned hanging out with history/poli sci majors. All knowledge is good, right?

There is a difference between nitrogen and nitroglycerin! "Dry ice" is yet another creature, frozen CO2, which "sublimes" (goes directly from solid to gas without passing through a liquid state). Water ice can do that too under the right conditions, like when your ice cubes shrink in the freezer.

Dry ice also can cause burns, if handled carelessly. Any of them, under the wrong conditions, can suffocate you. The possibility of someone blowing up a plane with nitroglycerine is very low on my threat list, but I can imagine scenarios of "harmless"-looking amounts of frozen CO2 causing problems in a passenger cabin, due to assumed familiarity�it looks cool! It won't catch fire! We use it for theatrical effects all the time!

(Don't ask me how much is unharmless unless you can teach me lots more about cabin HVAC systems than I know now, but I suspect it's less than one might think.)

A five pound block of dry ice (which will probably sublime faster than normal due to the lower cabin pressure) will not change the level much in a large aircraft. The 150 passengers are continuously producing 12 pounds per hour of CO2. The aircraft ventilation system brings in enough air and exhausts the same to purge the CO2 being produced by the pax. Take 25 pounds of dry ice on a medium jet and sublime it in one hour and at most you only triple the CO2 level to about 1000 PPM which is still below the danger level. Only the most sensitive will notice discomfort at this level.

(OT: Dry ice is a problem on cargo aircraft. Sensitive materials are often shipped on dry ice, note on a Fedex shipping form it asks about dry ice and the amount. If dozens of packages happen to end up on one flight, the total amount might be considerable; their computer adds up the total amount of every flight. With no pax, cargo planes have less ventilation. Fresh air = heated air = engine bleed air = fuel burned. When I used to ship dry ice a dispatcher told me that above a certain number of pounds the pilots are required to wear their oxygen masks the entire flight which is not comfortable and the pilots hate it. )

Dry ice placed in a sink with running water or flushed down the airplane toilet system would do what? Create a spectacle?

Is ice cream allowed through the TSA screening checkpoints?

Yes, it can create a false positive. It doesn't do it regularly, but it can. Same with hand lotions that contain glycerin, but the hits are always small and they are easily cleared.

my mom had some kind of lotion or something that set it off. it was a weird situation, according to my brother who was there, because the TSO was real calm in stating "oh that just means its positive for explosives"